“Mr” stands for relative formula mass that can be used in the conservation of mass calculations. Calculations can be done to figure out the uncertainties in measurements and concentrations of a solution.
The relative formula mass of a substance is made up of molecules. A relative formula mass Mr of a compound can be calculated as the sum of relative atomic masses of all the atoms in the formula’s number. Ar is the relative molecular mass in the periodic table.
Ar of O (Oxygen) is 16 and Ar of C (Carbon) is 12
Mr of CO = 16 + 12 = 28.
Let us take another example of this.
For instance, you need to calculate the relative formula mass Mr of CaCO3, where it is given that the relative atomic mass of Calcium is 40; Oxygen is 16 and Carbon is 12.
Now let us see how we can calculate the Mr